Question 1

What process does yeast use to produce ethanol for automobile fuel from corn?

Accepted Answer

Yeast undergoes fermentation to produce ethanol from corn. This process involves anaerobic respiration in which sugars from corn are broken down by yeast to produce ethanol and carbon dioxide. The Krebs cycle and oxidation are part of aerobic respiration, not anaerobic respiration which is used in fermentation. Photosynthesis does not occur in yeast, but rather in plants and algae.

Question 2

All of the following are uses for ionizing or ultraviolet radiation EXCEPT

Accepted Answer

Ionizing or ultraviolet radiation is not typically used for heating cold food.

Question 3

Figure 28.2
 
-Figure 28.2 shows the growth curves of Acetobacter under different conditions.Which culture would produce the highest amount of the primary metabolite acetic acid?

Accepted Answer

The answer of Figure 28.2
 
-Figure 28.2 shows the growth...

Question 4

All of the following are industrial products produced using microbial fermentations EXCEPT

Accepted Answer

Saccharin is not produced using microbial fermentation. It is a synthetic sweetener produced through chemical synthesis. All other options listed are industrial products that are produced using microbial fermentations. Aspartic acid, citric acid, glutamic acid and riboflavin are all produced by different microbial strains and have various applications in the food, pharmaceutical and chemical industries.

Question 5

All of the following foods are produced using microbial fermentations EXCEPT

Accepted Answer

Ketchup is not typically produced through microbial fermentation. It is made from tomatoes, vinegar, sugar, and spices, without the fermentation process used in the production of sauerkraut, sour cream, yogurt, and certain types of coffee.

Question 6

What role do lactic acid bacteria play in cheese production?

Accepted Answer

Lactic acid bacteria play multiple roles in cheese production. They are responsible for curd formation, production of holes in Swiss cheese, ripening the cheese, and providing characteristic flavor and smell.

Question 7

Microorganisms themselves are commercial products.Which of the following microbes is available as (or in)a product sold in retail stores?

Accepted Answer

All of these organisms are used in commercial products: Bacillus thuringiensis in insecticides, Lactobacillus in probiotics, Rhizobium in agricultural inoculants to promote legume growth, and Saccharomyces in baking and brewing.

Question 8

Figure 28.2
 
-Which of the growth curves in Figure 28.2 is indicating the culture has reached the idiophase?

Accepted Answer

The idiophase is the stationary phase in bacterial growth, where the cells stop dividing and only increase in size or metabolic activity. In Figure 28.2, curve C shows a plateau phase, indicating that the culture has reached the idiophase. The other curves are still in the exponential phase, as the growth rate (slope of the curve) is still increasing.

Question 9

You are growing Bacillus subtilis,an aerobic bacterium that can also carry out fermentation,when required,in a bioreactor and notice that the growth rate has slowed and the pH has decreased.What could you add?

Accepted Answer

Bacillus subtilis is an aerobic bacterium indicating that it requires oxygen for growth. The decrease in pH could indicate the depletion of dissolved oxygen in the bioreactor. Therefore, adding oxygen will help to improve growth rates and maintain the pH. Adding glucose or lactose could contribute to acidification of the media and fermentation, which may not be desirable. Peptides could also be used as a nitrogen source for growth but would not address the decrease in pH. Lactic acid is a byproduct of fermentation and adding it would further contribute to the acidification of the media, making it a poor choice.

Question 10

All of the following are industrial enzymes made by microbial fermentations EXCEPT

Accepted Answer

Vitamin C is not an industrial enzyme made by microbial fermentation. The other choices, glucose isomerase, rennin, proteases, and amylases are commonly produced by microbial fermentations for various industrial applications.

Question 11

Aseptic packaging utilizes which of the following to sterilize laminated paper or plastic prior to filling with food?

Accepted Answer

Aseptic packaging commonly uses hot hydrogen peroxide solution to sterilize packaging materials such as laminated paper or plastic. This method ensures that the packaging is free from microorganisms before it is filled with food, maintaining the food's sterility and safety.

Question 12

The following steps are required for making cheese.What is the second step,which helps to provide the characteristic flavors and aromas of the cheese?

Accepted Answer

Inoculation with lactic acid bacteria is the second step, which helps in developing the characteristic flavors and aromas of the cheese through fermentation.

Question 13

Figure 28.2
 
-Which of the growth curves in Figure 28.2 will give the highest yield of a secondary metabolite?

Accepted Answer

Curve C represents the stationary phase, which is when secondary metabolites are typically produced at their highest levels. Therefore, choosing curve C would give the highest yield of a secondary metabolite.

Question 14

Canning preserves food

Accepted Answer

Canning preserves food by exposing it to high heat, which kills any bacteria or other microorganisms that could spoil the food. This allows the food to be stored for an extended period without the need for refrigeration. Aseptic packaging (A) involves sterilizing the packaging and the food separately and then packaging the food in a sterile environment. Exposure to chemicals (B) or radiation (D) can also be used to preserve food, but these methods are less common and can have safety concerns. Exposure to high pH (E) can be used for some types of food preservation, such as pickling, but is not typically used for canning.

Question 15

Figure 28.2
 
-Which of the growth curves in Figure 28.2 is indicating the culture has reached the trophophase?

Accepted Answer

The answer of Figure 28.2
 
-Which of the growth curves...

Question 16

Acidithiobacillus ferrooxidans is used for the recovery of ________ from ore.

Accepted Answer

Acidithiobacillus ferrooxidans is a type of bacteria that is commonly used in biomining, particularly for the recovery of copper from low-grade ore. This bacteria is able to oxidize sulfide minerals in the ore, which releases the copper and makes it easier to extract.

Question 17

You are growing Bacillus subtilis,an aerobic bacterium that can also carry out fermentation,when required,in a bioreactor and notice that the growth rate has slowed and the pH has decreased.You suspect the bacteria are

Accepted Answer

The decrease in pH suggests that the bacteria are producing acidic waste products through fermentation, which can occur when oxygen levels are limited or depleted. This is a common strategy for cells to continue generating ATP even in the absence of oxygen.

Question 18

Which of the following microbes produces a natural biopesticide?

Accepted Answer

Bacillus thuringiensis is a natural biopesticide that produces proteins that are toxic to insect larvae. It is commonly used as a biocontrol agent in organic farming and is highly specific in its activity, targeting only certain species of insects.

Question 19

Biomass is a renewable energy source derived from the organic matter produced by living organisms. All of the following are sources of biomass EXCEPT

Accepted Answer

Oxidation of metals is not a source of biomass as it does not involve living organisms or organic matter.

Question 20

As cheese ages,it gets

Accepted Answer

As cheese ages, it undergoes a process called proteolysis, which breaks down proteins into peptides and amino acids, increasing acidity.

Quiz 28: Applied and Industrial Microbiology